ARTÍCULO ORIGINAL/ORIGINAL ARTICLE

Quality of meat marmoratus during frozen storage

Calidad de filetes de yaque durante el almacenamiento en congelación

Qualidade de filetes do judiá Leiarius marmoratus durante o armazenamento congelado

Nubia E. Cruz-Casallas1*, Pablo E. Cruz-Casallas2, Héctor Suárez-Mahecha3

1 Ingeniera Agrónoma, Esp, MSc; 2MVZ, MSc, PhD 3 MVZ, PhD, Instituto de Ciencia y Tecnología de Alimentos ICTA; Universidad Nacional de Colombia, sede Bogotá 2 Grupo de Investigación sobre Reproducción y Toxicología de Organismos Acuáticos (GRITOX). Instituto de Acuicultura, Universidad de los Llanos, Villavicencio, Colombia * Email: [email protected]

Recibido: agosto 16 de 2013. Aceptado: mayo 25 de 2014.

Abstract

The objective of this research is to establish the variation of the physicochemical, microbiological and sensory properties of vacuum packed fillets of catfish Leiarius marmoratus from wild and farmed, after 120 days of storage at -18°C.It was observed that the meat from the two sources presents protein content be- tween 19.8±0.2 and 20±1.1% and lipid content between 1.5±0.3 and 4.6±0.3%. The maximum values of aerobic mesophilic and total coliforms were 5.2±0.1 log cfu/g and 9±2 NMP/g, respectively, with significant variation (p <0.05) over time. The aerobic psychrophilic count was less than ten, the fecal coliforms less than 3 MPN/g, the S. aureus coagulasabelow100 cfu/g,and the Salmonellaspand Vibrio sp undetected. The pH reported in the range 6.5±0 to 7.1±0.2; the maximum valueof TVB-N were 15.3±0.2 mg of VBN/100 g, and the TBA was lower than 0.1 mg of MDA/kg with significant differences (p<0.05) during the 120 days of storage. The sensory analysis and texture had no significant differences (p>0.05) during storage. These results infer that catfish meat obtained from wild and farmed under the evaluated storage conditions have a shelf life greater than 120 days.

Key words: Fish meat,microbiological analysis, physicochemical analysis, sensory analysis, shelf life.

Resumen El objetivo fue establecer la variación de las propiedades fisicoquímicas, microbiológicas y sensoriales de filetes de yaque Leiarius marmoratus, silvestres y de cultivo, empacados al vacío y almacenados durante 120 días a -18 º C. Se observó que la carne de las dos fuentes, presenta contenidos de proteína entre 19.8 ± 0.2 y 20 ± 1.1 % y de lípidos entre 1.5 ± 0.3 y 4.6 ± 0.3 %. Los valores máximos de coliformes y mesófilos aerobios totales fueron de9±2 NMP/g y 5.2 ± 0.1 log ufc/g, respectivamente; variando signifi- cativamente (p<0.05) en el tiempo. El recuento de psicrófilos aeróbicos fue menor de 10, los coliformes fecales menos de 3 NMP/g, elS. aureus coagulasa estuvo por debajo de 100 ufc/g y la Salmonella sp y el Vibrio sppor debajo de los niveles detectables. El pH varió entre 6.5 ± 0 y 7.1 ± 0.2; los valores máximos

Calidad de filetes de yaque Leiarius marmoratus durante el almacenamiento en congelación 43 de TVB-N fueron 15.3 ± 0.2 mg de VBN/100 g, y el TBA fue inferior a 0.1 mg de MDA/kg, con diferen- cias significativas (p < 0.05) durante los 120 días de almacenamiento. El análisis sensorial y la textura no presentaron diferencias significativas (p>0.05) durante el almacenamiento. Estos resultados permiten inferir que la carne de yaque silvestre y de cultivo, bajo las condiciones de almacenamiento evaluadas, pueden tener una vida útil superior a 120 días.

Palabras clave: Análisis fisicoquímicos, análisis microbiológico, análisis sensorial, carne de pescado, vida útil.

Resumo O objetivo foi estabelecer a variação das propriedades físico - químicas microbiológicas e sensoriais dos fi- letes do yaque Leiarius marmoratus, selvagens e de criação, embaladas a vácuo e armazenadas por 120 dias a -18 ° C. Observou-se que a carne das duas fontes apresenta conteúdos de proteína entre 19.8 ± 0.2 e 20 ± 1.1 % e 20 ± 1.1 % e de lipídeos entre 1.5 ± 0.3 y 4.6 ± 0.3 %. Os valores máximos de coliformes e mesófilos aeróbios totais foram de 9 ± 2 NMP/g e 5.2 ± 0.1 log ufc/g, respectivamente; variando significantemente no tempo (p < 0.05). A contagem aeróbia de Psicrofílicas foi menor que dez, os coliformes fecais menos que 3 NMP/g, a S. aureus coagulasasob 100 ufc/g, e a Salmonella sp e o Vibrio spabaixo dos níveis detectáveis. O pH variou de 6.5 ± 0 e 7.1 ± 0.2; os valores máximos de TVB -N foram de 15.3 ± 0.2 mg de VBN/100 g e o TBA foi inferior a 0.1 mg do MDA/kg, com diferenças significantes (p<0.05) durante os 120 dias de armaze- namento. O analise sensorial e da textura não apresentaram diferenças significantes (p>0.05) durante o arma- zenamento. Estes resultados permitem inferir que a carne de yaques silvestres e de criação, sob as condições de armazenamento avaliadas podem ter uma vida util superior aos 120 dias.

Palavras-chave: Análise físico-química, análise microbiológica, análise sensorial, a carne, a vida dos peixes.

Introduction In catfish meat, as in all meats, the deterioration pro- cess starts as soon as the fish dies, including the deg- Fish meat has been positioning itself as a staple of a radation of proteins and ATP, altered pH, fat oxida- healthy diet because it is considered a source of high tion and production of undesirable compounds such quality food (Suárez-Mahecha et al., 2002), but the nu- as trimethylamine (TMA-N) and volatile bases of low tritional and physical characteristics can vary consid- molecular weight (TVB-N), which are produced by erably between and between individuals of the bacterial action and generate changes in texture, col- same species; and are related to the microbiological or, odor and flavor (Li et al., 2011). These changes quality of the cultivation water, body size, tempera- can be classified as biochemical, physical and micro- ture, hygiene during handling, harvest and slaughter biological, and determine the degree of acceptance methods, packaging, transport and storage, among by consumers and, along with nutritional valuation, others, which not only alter the characteristics of live shelf life (McMillin, 2008). Thus, Colombian law, fish, but also affect the shelf life of the final product specifically the Colombian Technical Standard NTC (González et al., 2009; Rodríguez et al., 2009). 4348, has established maximum allowable limits to identify the acceptable quality level for some param- Catfish farming is a growing industry worldwide, with eters, such as 400 CFU/g for E. coli, 1000 CFU/g for production in 2005 of over a million and a half tons of S.aureus coagulasa and absence of Salmonella spp meat, mainly based on the cultivation of Ictaluruspunc- and Vibro cholera in 25 g of meat. These rates apply tatus and two species of Pangasius spp (P. bocourtti and to all species of fish, even disregarding the variability P. sutshii) (FAO, 2011); in 2011, this amount was seen within and between species. just with the production in Vietnam of Pangasiusspp, which was intended only for international markets Leiariusmarmoratus, commonly known as yaque or (FAO, 2012). However, the quality of the meat of these black catfish, is a native siluridin the basins of the Am- catfish is now being questioned, not only in the con- azon, Orinoco and Essequibo rivers; and has generat- text of nutrition specifically related to the content and ed interest because it is specie that not only adapts to ratio of fatty acids, but also the physical and chemical cultivation conditions, but also possesses characteris- alterations caused by handling conditions used during tics similar to those of commercial catfish. Currently, production, processing and marketing. trade in these species depends 100% on natural ex-

44 ORINOQUIA - Universidad de los Llanos - Villavicencio, Meta, Colombia. Vol. 18 - No 1 - Año 2014 traction, but recent studies have identified the potential Proximate composition of these species for use in the process of diversifica- tion of aquaculture in Colombia (Cruz-Casallas et al., Proximate analysis was performed on day zero of stor- 2011), but currently the quality of the meat has not age to determine humidity (No. 952.08), crude protein been determined in order to establish processes that (No. 955.04), crude lipid (No. 948.15) and ash (No. allow management to potentiate their qualities. There- 938.08), using the methodology of the Association of fore, the objective of this research was to determine Official Analytical Chemists (2005). the chemical, physical, microbiological and sensory characteristics of yaque meat, both for wild and farmed Quality Analysis over a period of 120 days of storage under freezing conditions at -18 °C. On days 0, 15, 30, 60, 90 and 120 of storage, at ran- dom and for each source, five 100g fillets were re- Materials and methods moved from the freezer for the physical-chemical and microbiological analyses and 300g fillets for sensory 15 specimens of yaque catfish (Leiariusmarmoratus) testing. The samples were thawed at 4 °C for 6 hours were used, captured from the Guaviare river in the and homogenized in a domestic-use food processor municipality of San José del Guaviare (Guaviare - Co- (Oster®, EEUU), except for the texture and sensory lombia) with an average size and weight of 58.9±5.6 analysis, which used whole fish. cm and870±87g, respectively, and 25 specimens with an age of 20 months from commercial cultivation, ob- Microbiological analysis tained from the El Paraíso fish farm in the municipality of Cumaral (Meta-Colombia). These individuals were Using 11 gram samples, the study employed serial di- obtained by artificial reproduction, induced with carp lutions of 10-1, 10-2, 10-3with sterile peptone water, pituitary extract and cultivated in earthen ponds at a which were used for the aerobic mesophilic and psy- density of 1 /m2, fed ad libitum with a com- chrophilic counts, total and fecal coliforms and Staph- mercial ration of 30% crude protein and with an av- ylococcus coagulasa positive (NTC 4779, 2007). The erage weight of 625±133g and average fork length of aerobic mesophilic and psychrophilic microorganism 45.2±2.9 cm at harvest. counts were performed after incubation at 35 ± 2 ° C for 48 h with 1 mL of each dilution for mesophilic The fish were killed by cranial incision and the car- and 4 ± 0.5 ° C for 7 days for psychrophilic, using the casses were transported to the facilities of the Institute SPC agar culture medium (Merck KGaA, Germany), of Aquaculture of the Llanos University in Villavicen- reporting data as colony forming units CFU / mL (IN- cio (Meta-Colombia), packed in Styrofoam boxes cov- VIMA, 1998). ered with ice. Then the meat was washed with potable water and the skin was separated. Then, fillets were cut The total coliform count was made dispensing Bri- at the level of the and anal opening. la broth (Thermo Fisher, EEUU) in test tubes with a Durham tube, and incubated with 1 mL of each dilu- For each one of the sources, 25 fillets of 300g and 30 tion at 35±2 °C for 48 hours. With the positive tubes, fillets of 100g were obtained, which were packed in the fecal coliform count was performed, inoculated in polyethylene Food Saver® bags (NYSE:JAH, EEUU) 1 mL 2% Brilalactose broth and tryptophan broth (Mer- and vacuum sealed with hand sealing Food Saver® ck KGaA, Germany) and incubated at 44.5±0.5 °C for equipment (NYSE:JAH, EEUU). Samples were refriger- 48 hours in a water bath; confirmation of indole pro- ated (4°C) and transported to the Instituto de Ciencia y duction was performed with 2 mL of Kovac’s reagent Tecnología de Alimentos ICTA at Universidad Nacio- (SAR Ltd, England). Data were reported according to nal de Colombia (Bogotá-Colombia), where they were the MPN table. The Staphylococcus coagulasa positive held in frozen storage at -18 °C until use. count was performed by plating dilutions of 10-2 and 10-3 in Baird Parker Agar (Merck KGaA, Germany) in- The analysis of the samples was performed in triplicate cubated at 37 °C for 48 h, then the coagulase test was according to the Colombian Technical Standard NTC used for suspicious colonies, along with Gram stain- 4348 (2009) which specifies the requirements of whole ing(INVIMA, 1998). fish, medallions and pieces, chilled or frozen, suitable for human consumption; and supplemented with NTC For determination of Vibrio cholerae, 25g samples 5443 (2006), which specifies the requirements for the were used in 225 mL of alkaline peptone water (3% handling, transportation and marketing of aquaculture NaCl) and incubated at 35±2°C for 6 h, and plated in species: cachama, tilapia and trout. TCBS agar (Thermo Fisher, EEUU) at 35±2 °C, for 48

Calidad de filetes de yaque Leiarius marmoratus durante el almacenamiento en congelación 45 hours. To determine the presence of Salmonella sp, 25 532nm. To measure the concentration of MDA in the g of each sample were incubated in 225 mL of lactose sample, a calibration curve of nine points was used, broth (Thermo Fisher, EEUU) for non-selective pre-en- with 1,1,3,3-tetrametoxypropano as a standard com- richment at 37 °C for 24 hours. Then, 1 mL was used pound. The results were expressed as mg of MDA/ in selenite cystine broth (Thermo Fisher, EEUU) and kg of sample. 1 mL tetrathionate broth base (Thermo Fisher, EEUU) for selective enrichment, finally plating was done with For determination of pH, the study used a 10g homog- XLD (Thermo Fisher, EEUU) and Bismuth sulfite agars enized sample and 30mL of distilled water, agitated (Merck KGaA, Germany). Confirmation was done with with a magnetic plate for 30 min and subsequent rest Gram staining and Rapid One biochemical test kit (10 min). The pH was measured with a potentiometer (Thermo Fisher, EEUU). Analyses were performed ac- Handy Lab PH11 model D-55014 (Schott Instruments, cording to NTC 1325 (INVIMA, 1998). Germany) (NTC 4348, 2009).

Physicochemical analysis To determine texture, thawed 1 cm3 pieces of meat were used, and measured by penetration force us- Determination of total volatile basic nitrogen (TVB-N) ing a texture analyzer (Texture Analyzer TAXT plus, was performed by the method proposed by Goulas EEUU). The force was recorded during compression and Kontominas (2007), performing distillation of 10 g in a texture curve with a probe with a diameter of 2 samples with 1 g of Mg oxide in a distiller (Kjeltec Sys- mm and a penetration speed of 60 mm/minute with tem 1002 Distilling Unit, Sweden). The distillate col- 5mm penetration. Data were expressed as Newton lected in a 25 mL Erlenmeyer with boric acid (2%) and force. Taschiro indicator drops, was titrated with hydrochlo- ric acid (0.1045 N). The total volatile nitrogen content For sensory analysis, a semi-trained panel of five peo- was calculated by the following equation: ple was used, using a hedonic scale of decreasing re- jection from 1 to 9, who evaluated appearance, color and smell of raw meat and color, aroma and flavor mg of VBN/100 g sample = in cooked meat, with a range of values from 1 corre- sponding to “dislike extremely” and 9 to “like extreme- In which: ly” (Kostaki et al., 2009). A sensory value of 4 was used as the minimum range of acceptability. The meat cook- Vs = Volume of hydrochloric acid used in the titra- ing process was done with a conventional stove (AR tion of the sample in mL. -T, Haceb®, Colombia), with immersion for 10 min in Vb = Volume of hydrochloric acid used in the blank potable water at a temperature of 100 °C. titration in mL. N = Normality of the HCl Statistical Analysis M = Sample weight in grams Data were statistically described and expressed as The thiobarbituric acid analysis (TBA) was done mean± standard error of the mean (SEM). Initially, the by the extraction method described by Wang and assumptions of homogeneity of variances and normal Xiong (Wang and Xiong, 2005), which quantifies the distribution of the data were verified, using Bartlett’s presence of byproducts of lipid oxidation (malonal- and Shapiro-Wilk tests. The results of the sensory anal- dehyde - MDA), through the reaction with thiobar- ysis were transformed using a natural logarithm. To bituric acid (TBA). 0.5 g samples were used, which compare the chemical composition between the two were carried in 25 mL Falcon tubes, adding 50 uL of sources, a student test was used and to determine the ethanolic solution of BHT butylated hydroxyl toluene effect of storage at 0, 15, 30, 60, 90 and 120 days on (5%), 3 mL of TBA (0.375%) and 20 mL of trichlo- the quality variables (microbial count, pH, TVB -N, roacetic acid (5% in 0.25 N HCl). The mixture was TBA and texture), analyzes of variance (ANOVA) was centrifuged for 4 min (2500 rpm) and then allowed carried out following the Tukey test for comparison of to react in boiling water (93 °C) for 40 minutes. An means. The nonparametric data reported in the senso- aliquot of 5 mL of the supernatant was centrifuged ry analysis were analyzed based on the Friedman test with 5 mL of chloroform at 5500 rpm for 20 min in followed by Dunn’s test. In all cases, we used the value centrifuge Heraeus MegafugeTM 16R (Thermo Scien- of p <0.05 to consider the existence of significant dif- tific, Germany) and then the absorbance was mea- ferences. For statistical analysis, we used the statistical sured in the aqueous phase in a spectrophotometer software Matlab® version 7.11.0.584 (R2010b, License UV-VIS Genesis 10S(Thermo Scientific, Germany),at No. 161051).

46 ORINOQUIA - Universidad de los Llanos - Villavicencio, Meta, Colombia. Vol. 18 - No 1 - Año 2014 Results Quality Analysis Proximate composition Microbiological analysis

The table 1 shows the results of proximate analy- Microbiological changes observed in the meat during sis performed on fresh fillets of wild and farmed. the 120 days of storage are shown in Table 2. The val- It was observed that farmed meat had higher con- ues indicate that all samples, both for wild and farmed, tents of moisture (77.2±0.8%), protein (20.0±1.1%) began and ended in acceptable microbiological condi- and ash (1.4± 0%) when compared with wild meat tions without exceeding the maximum allowed under (74.3±0.2%, 19.8±0.2% and 1.3±0.1, respectively), the Colombian Technical Standard NTC 4348. but without significant differences (p> 0.05); while for lipid content. A contrary behavior was seen, In the count for mesophilic organisms, was observed where wild meat had higher contents (4.6±0.3%) an increase over time, reaching a maximum of 5.2±0.1 than farmed meat (1.5±0.3%), with significant differ- log CFU/g for wild meat and 4.3±0.1 log CFU/g for ences (p <0.05). farmed, with significant differences (p <0.05) from 15 days of storage for the former source and from 90 days Table 1. Proximate composition (%) of L. marmoratus fillets for the latter source, respectively. In psychrophilic obtained from wild and farmed in earthen ponds. Data counts, they were not found to increase over time in presented as mean ±SEM (n =3). storage and in all cases, were less than one. The to- tal coliform count peaked at 6.0±1.0 MPN/g for wild, Provenance Moisture Protein Lipids Ash and at 9.0±2 MPN/g for farmed, with a significant dif- Farmed 77.2±0.8a 20.0±1.1a 1.5±0.2b 1.4±0.1a ference (p <0.05) from day 90 of storage. In counting Staphylococcus coagulasa positive is observed that for Wild 74.3±0.2a 19.8±0.2a 4.6±0.3b 1.3±0.1a wild meat and farmed meat, the maximum count not a,b Different letters between rows indicate statistically significant diffe- exceeded 100 log cfu / g, with no significant differ- rences according to Tukey test (p<0.05). ences (p> 0.05) throughout the storage time. Likewise,

Table 2. Variation of the microbiological quality of L. marmoratus fillets obtained from wild and farmed in earthen ponds, over a storage period of 120d under freezing conditions (-18°C). Data are mean ± SEM (n =3).

Days of Storage Provenance Variables 0 15 30 60 90 120 Mesophilic log UFC/g 3.2±0.0 a 2.7±0.0 b 4.0±0.1 c 4.7±0.1 d 4.7±0.1 d 5.2±0.1 e

Psychrophilic log UFC/g <1 <1 <1 <1 <1 <1

Coliform total NMP/g 5.4±0.9 3.1±0.1 4.8±0.6 6.0±0.0 5.5±0.9 6.0±1.0

WILD Coliform fecal NMP/g <3 <3 <3 <3 <3 <3

Salmonella sp Absent Absent Absent Absent Absent Absent

Vibrio sp Absent Absent Absent Absent Absent Absent

Staphylococcus coagulasa + ufc/g <100 <100 <100 <100 <100 <100

Mesophilic log UFC/g 3.7±0.1 a 2.9±0.0 a 3.1±0.1 a 3.0±0.0 a 3.0±0.0 b 4.3±0.1 c

Psychrophilic log UFC/g <1 <1 <1 <1 <1 <1

Total Coliform NMP/g 3.2±0.1 a 6.0±1.3ab 9.1±0.0abc 8.0±1.0 cd 8.6±1.5bcd 9.0±2.0 bcd

FARMED Fecal Coliform NMP/g <3 <3 <3 <3 <3 <3 Salmonella sp Absent Absent Absent Absent Absent Absent

Vibrio sp Absent Absent Absent Absent Absent Absent Staphylococcus coagulasa+ log <100 <100 <100 <100 <100 <100 ufc/g a,b,c,d Different letters within rows indicate statistically significant differences according to Tukey test (p<0.05).

Calidad de filetes de yaque Leiarius marmoratus durante el almacenamiento en congelación 47 no presence of Salmonellasp or Vibrio spwas detected allowable value (30 to 40 mg/100g of meat) set by NTC and fecal coliforms were lower than 3 MPN/g. 4348 exceeded.

Physicochemical analysis The peak TBA value (Figure 2a) of the wild meat was 0.09±0 mg of MDA/kg of sample, while for the farmed The figure 1 presents the means and standard error meat was 0.05±0 mg of MDA/kg with statistically sig- of the variation of pH and TVB-N and figure 2 shows nificant differences (p <0.05) from day 60 in the wild the means and standard error of the results obtained meat and day 90 for the farmed meat, but below the in terms of TBA and texture changes during the 120 maximum allowed (4 mg/kg) in fish meat in order to be days of storage at-18°C. The pH (Figure 1a) for the considered of good quality. In texture (Figure 2b), no two sources was found within the range of values of significant differences were found (p> 0.05), obtaining neutrality, with the wild meat in between 6.5±0 and values between 0.4±0.1 and 0.7±0.1 Newton force for 7.1±0.2 with significant difference from day 90 of stor- wild meat and between 0.4±0.1 and 0.6±0.1 for the age and farmed meat between 6.6±0 and 6.7±0 with farmed meat. significant differences (p <0.05) from day 30 of storage. Regarding the formation of total volatile basic nitro- Sensory analysis gen (TVB-N) (Figure 1b), a progressive increase was observed over time, showing a decrease by day 60, The sensory evaluation results of L. marmoratus fillets, which was quickly recovered, reaching a maximum of vacuum packed and stored for 120 days at -18 °C, are 15.3±0.2 mg of VBN/100 g for wild meat and 14.0±0.5 presented in Table 3, showing that the two sources in mg of g VBN/100g for farmed meat. Similarly, it was sensory evaluation scored above 4 for all attributes and found that in no one of the cases was the maximum that the variation in time of storage showed no signifi-

a,b,c,d,e Different letters above the line indicate statistically sig- a,b,c,d,e Different letters above the line indicate statistically sig- nificant difference (p < 0.05) between days of storage as- nificant difference (p < 0.05) between days of storage as- Tukey test. Tukey test.

Figure 1. Variation of pH (a) and the concentration of Total Nitrogen volatile bases (b) of fillets L. marmoratus, obtained Figure 2. Variation of TBA (a) and the Texture(b) of fillets from wild and farmed in earthen ponds during 120 day L. marmoratus, obtained from wild and farmed in earthen storage under freezing conditions(-18°C).Data presented as ponds during 120 day storage under freezing conditions(- mean ±SEM(n =3). 18°C).Data presented as mean ±SEM(n =3).

48 ORINOQUIA - Universidad de los Llanos - Villavicencio, Meta, Colombia. Vol. 18 - No 1 - Año 2014 Table 3. Variationofthe sensory attributes of fillets L. marmoratus raw and cooked, from wild and farmed for 120dof storage under freezing conditions(-18°C). Data presented as mean ± SEM (n =3).

Origin and Attributes * Days of Storage 0 15 30 60 90 120 Raw Meat Appearence 7.4±0.7 7.2±0.9 7.2±0.6 8.0±0.3 7.2±0.6 8.2±0.2 Color 7.4±0.9 7.0±0.8 7.2±0.6 8.0±0.3 7.2±0.5 8.2±0.2 Smell 7.0±0.8 6.4±0.9 7.2±0.6 7.4±0.5 7.2±0.6 6.8±0.7 WILD Cooked Meat Color 5.8±1.0 7.2±0.7 7.4±0.5 6.8±0.5 7.6±0.5 8.0±0.0 Aroma 7.2±0.7 7.2±0.7 7.6±0.2 7.4±0.6 6.8±0.6 7.6±0.5 Flavor 7.4±0.7 7.6±0.4 7.2±0.8 7.2±0.6 7.4±0.4 8.0±0.0 RawMeat Appearence 6.0±1.1 6.8±0.7 6.6±1.0 7.2±0.5 7.6±0.7 7.2±0.7 Color 7.2±0.7 6.6±0.5 6.2±0.8 7.2±0.6 6.6±0.6 7.2±0.7 Smell 6.4±0.7 6.2±0.6 7.0±0.8 7.2±0.6 6.6±0.6 7.6±0.4 FARMED Cooked Meat Color 6.6±O.7 7.4±0.5 8.0±0.5 7.6±0.5 7.0±0.4 6.8±0.4 Aroma 6.2±0.9 7.8±0.2 7.4±0.4 7.2±0.4 6.6±0.8 6.6±0.7 Flavor 7.0±0.7 8.0±0.3 8.4±0.4 7.6±0.4 7.4±0.5 6.6±0.7

* Attributes ranked by hedonic scale decreasing 0-9.the value of 1correspondingto “dislike extremely”, 9 “like extremely”, with 4 being the minimum range of acceptability as Kostaki et al., (2009). cant differences for indicating an alteration in the shelf assigned to Clariasgariepinus and Ictaluruspunctatus fil- life. In wild meat, the lowest attribute valuation was lets (Ersoy and Özeren, 2009; Li et al., 2009). On the the smell of raw meat, which scored between 6.4±0.9 other hand, fillets from farmed individuals are classi- and 7.4±0.5 during the sampling, and color in cooked fied as “lean meat”, equal to the rating given to Pseu- meat with a rating between 5.8±1.0 and 8.0±0; while doplatystomafasciatum, Pseudoplatystomacorruscans, in the farmed meat, the lowest qualified attribute was Pangasiushypophthalmus and Pangasianodongigas (Or- color and smell of raw meat with a rating that fluctuat- ban et al., 2008; Martino et al., 2002; Perea et al., 2008; ed between 6.2±0.8 and 7.2±0.7 and between 6.2±0.6 Chaijan et al., 2010). and 7.6±0.4, respectively, and the aroma in cooked meat which a variation between 6.2±0.9 and 7.8±0.2. It is widely known that high levels of lipids in the meat of fish increase susceptibility to oxidative rancid- ity and therefore, the onset of degradation processes Discussion (Pacheco et al., 2010), which added to the microflora are determinants of product quality. Therefore, it can According to the results of the proximate analysis per- be inferred that wild meat possesses a greater risk of formed on the fresh fillets of yaque L. marmoratus meat, degradation than that of farmed meat, however, stor- it can be inferred that this species may be an important age conditions (-18 °C and vacuum packaging) not source of food, in which the protein content is not only only impede the growth of microorganisms but also within the average reported for fish meat in general (17 decrease susceptibility to autohydrolysis and conse- and 21%) (Gil, 1989), but is superior to other commer- quently the degradation of the meat (Kubitza, 2012). cially important catfish such as Pangasiushypophthalmus The International Commission on Microbiological (12.65 to 15.59%), Clariasgariepinus (15.71 to 16.2%) Specifications for Foods- ICMSF (2005) believes that and Ictaluruspunctatus (18.1%) (Orban et al.,2008; Er- the level of microbial contamination in the muscle at soy and Özeren, 2009; Li et al., 2009). Also, the lipid which fish show signs of alteration is 7.0 log cfu/g. In content provides significant energy and, according to the present research, the mesophilic and psychrophilic the classification proposed by Castro-González (2002), counts did not exceed this value in any one of the sam- meat from individuals captured in the wild can be con- plings, which is the reason why the meat retained good sidered as “medium fatty”, similar to the classification characteristics. Lubes (2005) and Noseda et al. (2012)

Calidad de filetes de yaque Leiarius marmoratus durante el almacenamiento en congelación 49 conducted microbiological assessments on catfish fil- ing the behavior of the meat with regard to the lipid lets under different preservation processes, involving content. This indicates that, although wild meat pres- the use of packaging of low and high permeability and ents increased susceptibility to oxidative rancidity, modified atmospheres, and found counts greater than observed concentrations did not exceed the values 6 log cfu/g for total aerobic mesophilic and greater needed to be considered a low-quality meat (4 mg of than 7 log cfu/g for total aerobic psychrophilic; values MDA/kg of meat). In other catfish meat, such as Pseu- that were associated with the end of the product shelf doplatystomasp, Brachyplatystomarousseauxii, Bagre- life and which were related to the contents of TVB-N, marinus, this parameter has reached concentrations TBA and pH. of 5, 1.98 and 3.2mg of MDA/kg, respectively, under different preservation treatments and storage tempera- Regarding the pH, it was found that for both wild and tures (Rodríguez et al., 2009; Pacheco-Aguilar et al., farmed meat, the values remained within the range of 2000; Reyes and Arocha, 2000). neutrality during the 120 days of storage, probably due to the low content of glycogen. Thus, the results ob- In the texture analysis, the white muscle of the catfish tained for pH in this study were similar to those report- presented stable characteristics, due to the larger size ed in other catfish, with values ranging between 6 and of the muscle fibers, making it very efficient in indus- 7 under different storage conditions (Rodríguez et al., trial processes. However, the processes of freezing 2009; Pacheco et al., 2010; Lubes, 2005;Molina et al., and thawing during storage result in the formation of 2000; Chomnawang et al., 2007). ice crystals within the muscle fiber, causing structural damage and solute concentration in the meat, which In order to maintain the pH values as low as possible, in turn, lead to alterations in the biochemical reactions is important to maintain low temperatures during the at the cellular level and affect the physical quality pa- process of gutting and filleting(Pacheco et al., 2010), rameters of the meat (Leygonie et al., 2012). The varia- which minimizes degradative biochemical reactions tion in the texture of the L. marmoratus meat stored for involving the liberation of inorganic phosphate and 120 days at -18 °C showed no significant differences (p ammonia as a result of enzymatic degradation of ATP <0.05), indicating that for both types of meat the pro- and the buffering capacity of the proteins contained in cesses of freezing and storage did not cause alterations the fish muscles. of the muscle fiber structures.

Analyzing the results of the formation of total volatile Sensory changes in color, odor, flavor, taste and tex- basic nitrogen (TVB-N) of the two sources, progressive ture are related to the before mentioned parameters, increase over time was observed, but with a decrease but these sensory changes depend on the species and towards day 60, which was quickly recovered. This storage method. Since L. Marmoratus yaque meat pos- behavior is attributed to decreased autolytic activity sesses relatively low fat content, small concentrations and the beginning of the microbial degradation pro- of TBA and TVB-N and a low microbial activity, it is cess, which is common in all meats (Pacheco et al., expected that the shelf life will be longer in compari- 2010). Similarly, it was determined that these peaks son with other species such as salmon or trout. Rodrí- did not contribute to the production of undesirable guez et al.(2009), Pacheco et al. (2010),Lubes (2005), aromas in the product, so one would expect a high Noseda et al.(2012) Molina et al.(2000), Chom- level relationship between this variable and the results nawang et al.(2007) and Reyes and Arocha (2000) of a sensory evaluation of product acceptance (Massa, indicated that catfish meat smell and taste decrease 2006). In a study by Lubes (2005), it was concluded in value over time, due to the increase of metabolites that inLeiariusmarmoratusfillets, when was exposed and degradation products of ammonia compounds, to different retention times before being stored at 0°C, but that the implementation of management practic- the TVB-N content had values between 13.8 and 20.7 es such as washing with chlorine, salting or modified mg VBN/100g of muscle, without reaching in any case atmosphere or vacuum packaging achieve increased the maximum during the 21 days of the study; while product shelf life of up to 84 days when stored at Chomnawang et al., (2007) reported that the hybrid freezing temperatures (-16 to 0 °C) and up to 20 days Clariasmacrocephalus× Clariasgariepinus reached the at refrigeration temperatures (2 to 4 °C). In this study, maximum allowable level of TVB-N only after 9 days it was shown that the shelf life of L. marmoratus ya- when stored in polyethylene bags at 4 °C (Rodríguez que meat can exceed the evaluated storage time and et al., 2009). that the storage temperature and probably the type of packaging contributed to the fact that attributes such In turn, the content of TBA showed peak values that as color, flavor and aroma were not altered, both in did not exceed 0.1 mg of MDA/Kg of meat, reflect- raw and cooked meat.

50 ORINOQUIA - Universidad de los Llanos - Villavicencio, Meta, Colombia. Vol. 18 - No 1 - Año 2014 Conclusions Goulas AE, Kontominas MG. Combined effect of light sal- ting, modified atmosphere packaging and oregano essential oil on the shelf-life of sea bream (Sparus au- We conclude that L. marmoratus yaque meat, from rata): Biochemical and sensory attributes. Food Chem, both wild and farmed, when vacuum packed and fro- 2007;100(1): 287-296. zen at -18 °C, presents quality characteristics such as ICMSF. Micro-organisms in Food 6: Microbiological Ecology pH, TBA, TVB-N, texture, microbiological count and of Food Commodities. Second Edition. Ed. Plenum Pu- sensory analysis within the acceptable ranges for hu- blishers, USA, New York; 2005; 734p. man consumption and that, under these conditions, INVIMA. Manual de técnicas de análisis para control de cali- the meat may have a shelf life longer than 120 days. dad microbiológico de alimentos para consumo huma- no. Ed. INVIMA. 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